2. Field of the Invention
The present invention relates to a thermoplastic sound insulation pad for inhibiting sound transmission between floors. The pad is comprised of a thermoplastic material having a three-dimensional shaped surface. The invention also relates to a sound rated floor system using the sound insulation pad. The invention further relates to a method of constructing such a sound rated floor system.
2. Related Background Art
The transmission of sound between floors in multistory dwellings and commercial buildings can be a serious problem. The sound that is transmitted between floors is usually due to either impact sound generated on the floor or airborne sound. The transmission of sound between floors may disturb or be an annoyance to the users of the area below the room in which the sound is generated.
In general, impact sound is generated due to pedestrian footfall on the floor, movement of heavy objects over the floor and any other contact made with the floor. Airborne sound is usually due to speech or music. The transmission of sound between floors is particularly a problem where the upper finished flooring is made of concrete, ceramic tiles, or hardwood. Installation of thick carpeting may be required in order to prevent the transmission of sound. However, in heavy traffic areas such as restaurants, hospitals, government buildings and other commercial buildings this may not be a practical solution. The use of carpeting may result in an increase in building operation expenses due to additional maintenance, cleaning and floor covering replacement cost. Moreover, the use of a hard floor surface such as ceramic tiles, stone and the like in a heavy traffic area is more desirable due to the greater durability of the flooring and the ease of maintenance. An alternative to the use of carpeting to prevent sound transmission has been the use of a sound rated floor system or a floating floor. The use of a sound rated floor system or a floating floor substantially reduces the transmission of sound between floors by isolating the flooring from the floor substructure.
A sound rated flooring is disclosed in U.S. Pat. No. 4,685,259 which comprises a sound attenuation layer having a composite panel structure which is placed on a subfloor. The composite panel structure has a core and at least one acoustically semi-transparent facing of fibrous material bonded to the core and a rigid layer on the sound attenuation layer. The core of the composite panel structure is a walled structure such as a honeycomb formed of cardboard, kraft paper or aluminum. The facing placed on the core is a fibrous material such as fiber glass.
A rigid layer is placed on top of the attenuation layer to support the upper finished flooring.
In a floating floor system an intervening sound isolating layer is incorporated between the walking surface and the joists of the floor. Sound isolating materials such as foamed rubbers or mineral wools are used to create a sound insulating layer between the floor and the floor support joists. However, the use of floating floor construction in upgrading an existing floor results in an increase in its thickness, which may result in a loss of clearance for door openings. In U.S. Pat. No. 4,879,856 a floating floor system for use with joisted floors is disclosed which does not substantially raise the level of the floor. Inverted channel section floor supports are mounted longitudinally on the floor joists. The inverted channel has outwardly directed flanges between the joists. Sound insulation material is interposed on the outward directed flanges between the joists. The flooring is extended over the insulation material and secured to the joists.
Another method used to prevent the transmission of sound between floors has been the use of a sound control matting designed by AKZO industries in conjunction with the Ceramic Tile Institute (CTI) and sold under the trademark name ENKASONIC. ENKASONIC is a 0.4 inch thick matting composed of nylon filaments forming a three-dimensional geomatrix with a non-woven fabric which is heat bonded to the upper surface of the nylon. ENKASONIC matting is used in the construction of a subfloor to prevent the transmission of sound between floors.
The use of elastic foam to prevent the transmission of sound through a floor is also known in the prior art.
In U.S. Pat. No. 4,681,786 a horizontal-disassociation-cushioning layer underneath a tile floor is disclosed. The horizontal-disassociation-cushioning layer is a sheet of elastic foam from about 1/8 to 1/2 inch thick. The presence of the horizontal-disassociation-cushioning-layer in the floor construction substantially diminishes the transmission of impact sound to the area below the floor.
The present invention provides for a sound insulation pad that is effective in reducing the transmission of sound between floors. Additionally, the disclosed sound insulating pad permits a cost-effective method for preventing sound transmission either in existing floors which are being upgraded or in the construction of new floors.